In heating the interiors of buildings and of building floors, several conventional heating methods have been employed, including hot water/steam and forced air heating. Generally, these heating methods require the installation of large air ducts or extensive water piping, both of which take up a considerable amount of space within a building and require careful planning for locations of vent, radiators and so forth. Vents and ducts tend to obstruct living and working areas within a building and require other components of the building (ceilings, walls, etc.) to be designed around them. Some hot water systems include piping which is embedded in a flooring or ceiling material through which warm water is circulated to heat a building. In some geographic localities, however, electrical power is cheaper than gas, and direct electric heating is desired.
Electric heating cables have been employed to heat cement slabs and the like by being positioned in a layer beneath the slabs. High limit switches have been employed adjacent the cables to sense the cable temperatures and to prevent the cables from over heating. Temperature sensors imbedded in the concrete slabs regulate the electric current supplied to the heating cable, thereby regulating room heat by controlling the temperature of the concrete where the electric heating cables are embedded. Positioning the temperature sensors in the room air space above the flooring results in prohibitively long response times.
Other systems have been proposed for positioning under stone or ceramic tile, carpet, linoleum and the like for heating the covered floor area. When used with tile, the systems are applied directly onto the substrate or subfloor. These systems suffer many deficiencies. For example, the prior art systems as discussed below are expensive to install, difficult to maintain and/or have many safety problems.
U.S. Pat. No. 5,461,213 to Rodin discloses a heated floor construction which includes a supporting structure or an existing floor construction having a number of components of sheet material, at least one electric heating cable and a device for regulation of the heat dissipation of the heating cable. The heating cable is disposed in at least one channel between the different sheet components. This reference does not disclose a system which utilizes a panel member having a reflective barrier layer for reflecting heat generated by a heating element away from the sub-floor and toward the flooring.
U.S. Pat. No. 5,004,895 to Nishino et al. relates to a heater device used for a flow material with a heater contained therein, the heater device having an insulating sheet, a plurality of belt shaped electrodes, a plastic radiant body and an insulating layer formed on an upper surface of the radiant body layer. This reference does not disclose a system which utilizes a panel member having a reflective barrier layer for reflecting heat generated by a heating element away from the sub-floor and toward the flooring.
U.S. Pat. No. 4,990,744 to Willner provides for an underfloor covering heating system for positioning below a floor covering a system including a heat conducting substrate within which is positioned solid conductor resistance heating wires in a serpentine manner for heating the substrate. This reference does not disclose a system which utilizes a panel member having a reflective barrier layer for reflecting heat generated by a heating element away from the sub-floor and toward the flooring.
U.S. Pat. No. 4,878,332 to Drake discloses an electric radiant heating system having an electric resistance heating cable embedded in a cementious thermal mass for transferring thermal energy to the thermal mass when an electric current is applied to the cable. This reference does not disclose a system which utilizes a panel member having a reflective barrier layer for reflecting heat generated by a heating element away from the sub-floor and toward the flooring.